CN111367235A

CN111367235A - Diagnostic maintenance system of numerical control machine tool

Info

Publication number: CN111367235A
Application number: CN201910981306.2A
Authority: CN
Inventors: 三角进; 村田正嗣
Original assignee: Nikken Kosakusho Works Ltd
Current assignee: Nikken Kosakusho Works Ltd
Priority date: 2018-12-26
Filing date: 2019-10-16
Publication date: 2020-07-03
Anticipated expiration: 2039-10-16
Also published as: EP3690567A1; CN111367235B

Abstract

The invention relates to a diagnosis and maintenance system of a numerical control machine tool, which is a labor-saving technology capable of monitoring and diagnosing a plurality of numerical control machine tools. The host computer device downloads the monitoring management program to the numerical controller of the numerical control machine tool (NC) in step S10, collects numerical control information input and output between the numerical controller and the servo motor in step S30, analyzes the monitored numerical control information in step S40, and diagnoses the numerical control machine tool in steps S50 to S110.

Description

Diagnostic maintenance system of numerical control machine tool

Technical Field

The present invention relates to a system which is connected to a numerical control machine tool belonging to a numerical controller and which can diagnose whether the numerical control machine tool is operating correctly.

Background

In a numerical control machine tool (numerical control device, or nc (number control)) that performs cutting processing of a workpiece (work) by numerical control, there are known techniques for calculating a backlash (back lash) amount provided inside the machine tool, and techniques for correcting a parameter relating to the backlash when the backlash amount exceeds an allowable range so as to avoid a processing failure, as described in patent documents 1 to 3.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese laid-open patent publication No. 9-201745

Patent document 2: japanese laid-open patent publication No. 2000-52178

Patent document 3: japanese patent application laid-open No. 2010-79845.

Disclosure of Invention

[ problems to be solved by the invention ]

Nowadays, the demand for labor saving and automation in factories has been gradually increased. In the case of the conventional technique, it is necessary to assign an operator for each numerical control machine tool to operate the control panel of the numerical control machine tool. Therefore, in a large factory where a plurality of numerically controlled machine tools are to be operated simultaneously, improvement in terms of labor saving is desired.

In view of the above circumstances, an object of the present invention is to provide a labor-saving diagnostic and maintenance technique for monitoring and managing a plurality of numerical control machine tools without assigning operators to each numerical control machine tool when diagnosing whether the numerical control machine tools are correct.

[ means for solving the problems ]

In view of the above, a diagnostic and maintenance system for a numerical control machine tool according to the present invention includes one or more numerical control machine tools, a host computer (computer) device, and a communication device for transmitting and receiving data between the numerical control machine tools and the host computer device, wherein the numerical control machine tool includes: a servo motor (servo motor) as a power source of the numerical control machine tool; and a numerical control part for numerically controlling the servo motor; the numerical control unit includes: a monitoring device for monitoring the numerical control information inputted and outputted between the numerical control part and the servo motor; and an uploading device for uploading the numerical control information monitored by the monitoring device to an upper computer device through a network device; the host computer device has a diagnosis and maintenance device which diagnoses the numerical control machine tool according to the uploaded numerical control information, downloads (downloads) numerical control parameters to the numerical control machine tool when the diagnosis result falls outside the allowable range and is within a usable range, and rewrites the numerical control parameters memorized in the numerical control machine tool.

According to the present invention, an operator can diagnose a plurality of numerical control machine tools by one host computer device, and maintain the numerical control machine tools according to the diagnosis result without assigning operators to each numerical control machine tool. The upper computer device can be arranged near a plurality of numerical control machine tools. Alternatively, the host computer device may be provided separately from a plurality of numerical control machine tools, or may be provided separately from a factory in which the numerical control machine tools are installed, thereby realizing a remote (remote) diagnosis system. In addition, the numerical control machine tools are distributed in a plurality of factories, and the upper computer device can be connected with the plurality of factories, thereby realizing the integrated diagnosis system. The communication device is not particularly limited, and may be, for example, a network device connecting one host computer device and a plurality of numerical control machine tools, a wired cable connecting one host computer device and one numerical control machine tool, or a short-range wireless communication device such as Wifi (registered trademark). The present invention properly rewrites the numerical control parameters of the numerical control machine tool, so that the numerical control machine tool can be adjusted by the numerical control parameters and can be operated accurately for a long time.

As a more preferable aspect of the present invention, when the diagnostic result diagnosed by the diagnostic maintenance device falls within the allowable range and within the usable range, the numerical control parameter is not rewritten, and when the diagnostic result diagnosed by the diagnostic maintenance device falls outside the allowable range and outside the usable range, a warning is output. The output of the warning can be, for example, a screen displayed on a host computer device. Or a screen that can be output and displayed on the numerical control machine tool via a network device, for example.

The numerical control information such as a program (program) command and a feedback (feedback) monitored by the monitoring device of the numerical control unit is not particularly limited. As an aspect of the present invention, the numerical control information monitored by the monitoring device is selected from servo data including: a speed command output from the numerical control unit to the servomotor; a torque command outputted from the numerical controller to the servo motor; a speed feedback unit for outputting a speed feedback signal to the numerical controller from a feedback device provided in the servo motor; position feedback, output from the feedback machine to the numerical control unit; and the difference (error) between the velocity command and the velocity feedback. The feedback device is not particularly limited, and may be a position sensor (sensor) or a speed sensor. The feedback device is, for example, an encoder (encoder) attached to the servomotor to detect a rotation angle of the servomotor.

The diagnostic and maintenance device can diagnose whether or not a servo-controlled movable unit, such as various movable units including a movement in the X-axis direction, a movement in the Y-axis direction, a movement in the Z-axis direction, a rotation a about the X-axis, and a rotation B about the Y-axis, is operating correctly. Furthermore, the diagnosis and maintenance device can maintain the numerical control machine tool according to the diagnosis result. Accordingly, the numerically controlled machine tool can be continuously used in a correct state. In one aspect of the present invention, the diagnostic and maintenance device calculates a backlash amount of an engagement position between a drive gear driven by a servo motor and a driven gear engaged with the drive gear, diagnoses whether the backlash amount is within an allowable range and a usable range, and rewrites a numerical control parameter according to the backlash amount when the calculated backlash amount is outside the allowable range and within the usable range. According to this configuration, for example, when the calculated backlash amount increases, the numerical control machine tool can be operated accurately using the new numerical control parameter after rewriting. Or when the backlash amount particularly increases, a warning is output.

In one aspect of the present invention, the monitoring and management program drives the servo motor in the forward direction first, and then drives the servo motor in the reverse direction, and the diagnostic and maintenance device calculates the backlash amount in the reverse rotation. The backlash of the reverse rotation of the mechanical system is calculated from the time before the mechanical system starts operating in the reverse direction and the feed command in the reverse direction. In order to accurately calculate the backlash amount, the speed command in the forward direction and the speed command in the reverse direction are preferably set to be in a low speed region rather than, for example, a high speed region in machining a workpiece. It is sufficient that the feed command angle in the forward direction and the feed command angle in the reverse direction given by the servo motor are sufficiently larger than a predetermined amount of backlash. Between the speed command in the forward direction and the speed command in the reverse direction, a speed command (dwell) may be inserted to stop the speed command by setting the speed to zero.

The backlash amount is calculated using a torque command for operating the drive gear. After the backlash amount of the machine system is reduced, the torque command increases because the torque for operating the drive gear and the driven gear greatly changes, and as one aspect of the present invention, the diagnostic and maintenance device analyzes the torque command output from the numerical control unit, determines that the driven gear of the machine system has started to operate due to the change in the torque command, and calculates the backlash amount.

Since the driven gear is larger than the driving gear, the driven gear is not uniformly used as a whole, and the use area may be uneven. As one aspect of the present invention, the monitoring management program drives the servo motor in the forward direction and the reverse direction at a plurality of positions of the driven gear as described above, and the diagnostic and maintenance device calculates the backlash amount at each of the plurality of positions, and diagnoses and maintains the numerical control machine tool based on the backlash amounts to correct a pitch error (pitch error) of the driven gear. According to this configuration, even when the engagement of the driven gear is biased to a specific region due to uneven use, uneven wear in this region can be diagnosed, thereby facilitating correct operation of the numerical control machine tool. As a combination of the driving gear and the driven gear, for example, a small-diameter worm screw and a large-diameter worm wheel (worm) are known. When the worm screw drives the worm wheel, the rotation angle of the worm wheel per rotation of the worm screw is called the pitch. According to the present invention, since the pitch error is corrected in each pitch of the worm wheel, and the pitch error of the worm wheel is corrected, the indexing accuracy of the worm wheel 28 can be ensured for a long period of time.

There are various methods for calculating the backlash amount. The servo control can be calculated based on the change of the servo data such as the torque command. The servo data is outputted at intervals of, for example, 1[ msec (millisecond) ] or less, and the variation is large, so that it is sometimes difficult to determine whether the servo data has changed. Therefore, as an aspect of the present invention, the diagnostic and maintenance device calculates the backlash amount by normalizing a torque command to be monitored, determining a time point when the torque command after the normalization continuously increases or decreases a plurality of times, and multiplying a time period from a time point when the servo motor starts to be driven in a reverse direction to a time point when the mechanical system starts to operate (i.e., a time point when the torque command greatly changes) determined by the logic (logic) of the normalization by a constant speed of the program command.

Alternatively, as another aspect of the present invention, the supervisory control program executes a stop to set the speed command to 0 after driving the servo motor in the forward direction and before driving in the reverse direction. The diagnostic and maintenance device stores a predetermined value as a torque limit value, detects a time when the monitored torque command exceeds the torque limit value after the stop (torque limit skip function), and calculates the backlash amount based on the time. According to this mode, the time required for the change of the torque command can be calculated by a simpler method than the leveling.

Alternatively, as still another aspect of the present invention, the monitoring device monitors an initial torque command which is a torque command at an initial stage of use of the numerical control machine tool, the uploading device uploads the initial torque command to the host computer device, and the diagnostic and maintenance device relatively compares the stored initial torque command with a torque command of the numerical control machine tool after several months of use, thereby calculating the increment of the backlash amount. According to this type, the diagnosis about the backlash amount can be performed accurately. After a few months, it may be one year later or several years later.

The driving gear and the driven gear of the numerical control machine tool may be the same rotating bodies, or may be a combination of a linear body and a rotating body, such as a rack and pinion (rack and pinion). Or a combination of balls and grooves as in a ball screw (ball screw). As one form of the present invention, the driving gear and the driven gear are a worm screw and a worm wheel, the worm wheel is coaxially provided on the rotating disk, and the worm screw transmits the driving force of the servo motor to the rotating disk. Accordingly, the wobbling of the maintenance rotating disk can be diagnosed.

[ efficacy of the invention ]

Therefore, according to the invention, whether each numerical control machine tool is reasonable or not can be known by monitoring a plurality of numerical control machine tools through one upper computer device. Moreover, labor-saving diagnosis and maintenance in a large factory having a plurality of numerically controlled machine tools and labor-saving diagnosis and maintenance in a plurality of factories are realized.

Drawings

Fig. 1 is a system configuration diagram showing an embodiment of the present invention.

Fig. 2 is a perspective view showing a numerical control machine tool according to the same embodiment.

Fig. 3 is a schematic diagram showing a configuration of a numerical control machine tool according to the same embodiment.

Fig. 4 is a schematic diagram showing servo control performed inside the numerical control machine tool.

FIG. 5(A), FIG. 5(B) and FIG. 5(C) are front views showing the meshing position of the gears,

fig. 5(a) shows a state after the backlash is reduced in the forward rotation, fig. 5(B) shows an enlarged view of fig. 5(a), and fig. 5(C) shows a state after the reduction is filled in the reverse rotation.

Fig. 6 is a flowchart showing numerical control performed in the same embodiment.

Fig. 7 is a graph showing a change in torque command in the same embodiment.

Fig. 8 is a graph showing an enlarged portion of the two-dot chain line shown in fig. 7.

Fig. 9 is a graph showing a change in torque command in the same embodiment.

Fig. 10 is a graph showing an enlarged portion of the two-dot chain line shown in fig. 9.

Fig. 11 is a graph showing the torque command of fig. 10 being flattened.

Fig. 12 is a graph showing the torque command of fig. 10 being flattened.

Fig. 13 is a graph showing the torque command of fig. 10 being flattened.

Fig. 14 is a graph showing the torque command of fig. 10 being flattened.

Fig. 15 is a graph showing a torque limit value of a modification example.

Description of the symbols

11 spindle

12 rotating disc

13 spindle drive unit

14 rotating disk drive unit

15 spindle support part

16 rotating disk supporting part

17 numerical control unit

18 tool library

21 tool fixing rack

22 tool

24. 25 pinion

26 worm shaft

27 worm screw

28 worm wheel

BL, BL1, BL2 backlash

EC encoder

NC numerical control machine tool

NW network device (communication device)

PC upper computer device

R1, R2 to Rm circumferential position

SA servo amplifier

SM servo motor

SW switch

TCMD Torque command

VCMD speed commands

PCMD position instruction

POSF position feedback

SPEED velocity feedback

time t1 to t12

Ta, Tb and Tc.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Fig. 1 is a system configuration diagram showing an embodiment of the present invention. The present embodiment includes: a plurality of numerical control machine tools NC #1, NC #2 to NC # n; an upper computer device PC; and a network device NW connected to these devices. When the plurality of NC tools NC #1 to NC # n are not particularly distinguished, they are also simply referred to as NC tools NC. As a modification not shown, only one numerical control machine tool NC may be used.

Each of the numerical control machine tools NC is a numerical controller (NC apparatus) and operates by execution of a numerical control program. The numerical control program includes a workpiece processing program and a monitoring management program. For example, the numerical control machine tool NC stores a workpiece machining program and numerical control parameters, and machines a workpiece into a desired shape by executing the workpiece machining program. During this machining, each NC operates appropriately according to the stored numerical control parameters. If each of the numerical control machine tools NC does not operate correctly, such as a delay in machining operation or deterioration in machining accuracy, the numerical control parameter is rewritten. Accordingly, each NC machine tool NC always operates correctly to machine a workpiece. Each NC machine tool NC monitors (monitors) numerical control information on its own numerical control, and uploads the monitoring result to the upper PC through the network device NW.

In the present embodiment, a group of n numerical control machine tools NC #1 to NC machine tool NC # n and a host computer device PC are connected by a network device NW. The network device NW is a wired cable or wireless device, and uploads data and downloads programs as indicated by 2-point arrows between the upper computer device PC and the lower numerical control machine tools NC. Each NC machine tool NC may be disposed separately from the upper computer PC. The plurality of NC tools may be disposed in the same factory or may be disposed in separate factories.

The data transmitted by the network device NW is a numerical control procedure or a numerical control message. As indicated by a downward arrow in fig. 1, the upper computer device PC of the present embodiment downloads or rewrites a workpiece machining program to each of the numerical control machine tools NC on the lower level, or downloads or rewrites a monitor management program to each of the numerical control machine tools NC on the lower level, or downloads or rewrites numerical control parameters to each of the numerical control machine tools NC on the lower level via the network device NW. If necessary, the upper computer device PC outputs an OFF/ON command to each of the lower numerical control machine tools NC via the network device NW as indicated by a downward arrow in fig. 1, so as to turn OFF/ON the power supply to each of the lower numerical control machine tools NC. Accordingly, each NC tool is restarted. Alternatively, each NC starts or ends a workpiece machining program or a monitoring management program updated by rewriting. The same applies to the new numerical control parameters after rewriting.

Each NC machine tool NC uploads information about each NC machine tool NC to the host computer device as indicated by an upward arrow in fig. 1. The uploading will be described later in detail.

Fig. 2 is a perspective view schematically showing a numerical control machine tool NC taken out. The numerical control machine tool NC includes: a main shaft 11; a rotating disk 12; a main shaft driving unit 13; a rotary disk drive section 14; a spindle support portion 15; a turntable supporting portion 16; a numerical controller 17; and a tool library (toolkit) 18.

The spindle drive section 13 supports the spindle 11 and rotates the spindle 11. The spindle support portion 15 supports the spindle drive portion 13, and moves the spindle drive portion 13 in the vertical direction (Z axis). The Z-axis movement indicated by an arrow in fig. 2 is performed by a servo motor, not shown, provided in the spindle support portion 15. A tool holder 21 and a tool 22 are mounted on the front end of the main shaft 11. In other words, the spindle 11 is movable in the Z-axis direction, and is further rotatable about the Z-axis.

The rotary plate 12 is, for example, a circular plate, and a workpiece, not shown, is fixed thereto. The rotary disk driving unit 14 incorporates a servo motor, not shown, for indexing the rotary disk 12. The turntable support portion 16 supports the turntable 12 and the turntable driving portion 14. The rotary disk 12 rotates in the a direction indicated by the arrow in fig. 2.

The numerical control machine tool NC further includes a servo motor, not shown, and moves the spindle 11 in the Z axis indicated by an arrow in fig. 2, moves the rotary table 12 in the X axis direction and the Y axis direction, and rotates the rotary table 12 in the a direction. The numerical control machine tool NC of the present embodiment performs at least one of movement in the directions along the X, Y, and Z axes and rotation a and rotation B around the X and Y axes. The servo motors are arranged to move in the directions of the respective axes. In other words, the present embodiment has 4 servomotors.

The tool magazine 18 assists in attaching/detaching/replacing the tool holder 21 attached to the spindle 11 by supplying the tool holder 21 and the tool 22 to the spindle 11 or receiving the tool holder 21 and the tool 22 from the spindle 11.

Fig. 3 is a schematic diagram showing a configuration of a numerical control machine tool NC. In fig. 3, only the configuration according to the present invention is shown, and other configurations, for example, the wiring of the heavy electric system, are not shown. The numerical controller 17 is connected to a plurality of servo amplifiers (servo amplifiers) SA #1 to SA # 4. A servo amplifier SA is connected to a servo motor SM, and outputs various commands to the servo motor SM. Each servo motor SM is provided with an encoder EC. The numerical controller 17 is connected to one encoder EC or a plurality of encoders EC #1 to EC #4, respectively, and detects the rotational speed of each servo motor SM and outputs the detected rotational speed to the numerical controller 17. The numerical controller 17, which receives the speed feedback of the servo motor SM from the encoder EC, performs feedback control of the servo motors SM (SM #1 to SM # 4). The numerical controller 17 is connected to the network device NW.

Fig. 4 is a schematic diagram of the control executed inside the NC machine tool shown together with the configuration. As a configuration inside the numerical control machine tool NC, a pinion (pinion) is coupled to a motor rotating shaft of the servo motor SM # 1. Pinion 24 meshes with pinion 25. The pinion 25 is coupled to a worm shaft 26 and a worm screw 27. The worm screw 27 meshes with a worm wheel 28. The worm wheel 28 has a much larger diameter than the worm screw 27 and is coaxially coupled to the rotary disk 12.

The encoder EC #1 outputs the SPEED feedback SPEED or the position feedback POSF of the servo motor SM #1 to the numerical controller 17. The speed command VCMD is obtained from a difference between the position command PCMD and the position feedback POSF of the rotary disk 12. Further, the numerical controller 17 obtains a torque command TCMD from the difference between the SPEED command VCMD and the SPEED feedback SPEED, and outputs the torque command TCMD to the servo amplifier SA #1 via a switch (switch) SW. The servo amplifier SA #1 amplifies the input torque command TCMD and outputs the amplified torque command to the servo motor SM # 1.

The servomotor SM #1 drives the pinion 24 in accordance with the input torque command TCMD, and this driving rotation is transmitted from the pinion 24 to the worm wheel 28 via the pinion 25, the worm shaft 26, and the worm screw 27, and the rotary disk 12 is indexed in accordance with the numerical control program.

The servo data such as the position command PCMD, the SPEED command VCMD, the torque command TCMD, the SPEED feedback SPEED, and the position feedback POSF shown in fig. 4 are monitored by the monitoring device of the numerical controller 17. The monitoring means continuous monitoring.

Incidentally, in order to improve the determination accuracy, the position command PCMD issued to the servomotor SM accompanying the execution of the monitoring management program is in a low speed region. In order to improve the work efficiency, the position command PCMD given to the servomotor SM in accordance with the execution of the workpiece processing program is directed from the low speed region to the high speed region.

The numerical controller 17 of the present embodiment diagnoses the backlash at the meshing position between the worm wheel 28 and the worm screw 27.

Fig. 5(a), 5(B) and 5(C) are front views showing the meshing positions of the gears, fig. 5(a) shows a state in which the worm screw is rotated clockwise to reduce the backlash in the forward rotation direction and to open the backlash in the reverse rotation direction, fig. 5(B) shows an enlarged view of fig. 5(a), and fig. 5(C) shows a state in which the worm screw 27 is rotated counterclockwise to reduce the backlash in the reverse rotation direction. In the present embodiment, the servo motor SM is driven in the forward direction by the supervisory control program to perform the operation shown in fig. 5 a, the speed command given to the servo motor SM is then set to zero (stopped) to set the rotation speed of the worm screw 27 to zero, a series of numerical controls for driving the servo motor SM in the reverse direction to perform the operation shown in fig. 5C are then performed, and the backlash amount BL in the reverse direction between the worm wheel 28 and the worm screw 27 is calculated from the numerical control information on the numerical controls (fig. 5B).

The numerical controller 17 includes: a program execution device for memorizing and executing the numerical control program; a monitoring device for monitoring the numerical control information; the uploading device uploads the monitored numerical control information to an upper computer device PC; and a parameter memory device for memorizing the numerical control parameter. The host computer device PC includes: a diagnostic maintenance device for diagnosing the NC machine tool NC; and a parameter rewriting device for rewriting the numerical control parameter. The host computer apparatus PC executes the control shown in fig. 6 based on the numerical control information uploaded from the numerical control unit 17. Fig. 6 is a flowchart showing control executed in the present embodiment. In the following description, a numerical control parameter of a control system for adjusting the backlash amount BL of the mechanical system is referred to as a backlash correction value.

First, in step S1, the host PC starts a trial run program, and the NC machine tool NC is caused to perform a trial run. The trial operation is, for example, a hot-engine operation, and each of the servo motors SM #1, SM #2, and … is rotated in an idle (idling) state to operate the numerical control machine tool NC. Accordingly, the numerical control machine tool NC is continuously maintained within a certain temperature range. Alternatively, the numerical control machine tool NC maintains the lubrication state of the machine system constant. When the trial run is completed, the process proceeds to the next step S2.

In step S2, the host computer PC reads the backlash correction value of the numerical control machine tool NC stored in the parameter storage device in advance during the previous operation, and stores the backlash correction value in a cache memory (cache memory).

In the next step S3, the upper computer PC temporarily rewrites the backlash correction value of the NC machine tool NC to 0. If a value other than 0 falls in the backlash correction value, this value is first instructed after step S10 described later, and the backlash amount BL is calculated from this value. Step S3 prevents this. After the following step S10, the backlash amount BL is calculated assuming that the backlash correction value is 0.

In the next step S10, the supervisory control program is downloaded from the host computer device PC to the numerical control machine tool NC via the network device NW. The monitoring management program is stored in the program execution device of the numerical control unit 17. In the next step S20, the monitoring management program of the numerical control machine tool NC is started.

In the next step S30, the NC machine tool NC executes the supervisory control program, drives the servo motor SM to rotate the worm screw, and then fills the backlash quantity BL of the reverse rotation as shown in fig. 5(C) for the backlash quantity BL shown in fig. 5(a) and 5 (B). Through this series of operations, the numerical controller 17 outputs the torque command TCMD to the servomotor SM at intervals of, for example, 1[ msec (millisecond) ], the encoder EC attached to the servomotor SM detects the SPEED feedback SPEED of the servomotor SM at intervals of 1[ msec ], and outputs the SPEED feedback SPEED to the numerical controller 17, and the SPEED feedback SPEED is input to the numerical controller 17. In the input and output of these commands (numerical control information), the monitoring device of the numerical control section 17 monitors these numerical control information (servo data), and the uploading device of the numerical control section 17 uploads the monitored numerical control information to the upper computer device PC via the network device NW. The upper computer device PC collects the uploaded numerical control information (servo data).

In the next step S40, the diagnostic maintenance device of the host computer device PC analyzes the numerical control information collected in step S30 and calculates the backlash amount BL. The backlash quantity BL may be calculated as a result of performing the operations of fig. 5 a, 5B, and 5C only once, but in order to improve the accuracy of the diagnosis, the backlash quantity BL may be determined by calculating the backlash quantity at a predetermined circumferential position Rx (for example, R1 of R1 to R8 in fig. 4) of the worm wheel 28 corresponding to a predetermined indexing angle of the rotary disk 12 a plurality of times, and determining the backlash quantity BL based on the results of the plurality of times of calculation. The result of the calculation by the plurality of times is, for example, an average value of the plurality of calculated backlash amounts, an average value of values of the plurality of backlash amounts excluding a maximum value and a minimum value, a median value of the plurality of calculated backlash amounts, or a mode of the plurality of calculated backlash amounts.

In the next step S50, the diagnostic and maintenance device of the host computer device PC checks whether the backlash quantity BL calculated in step S40 is within a predetermined allowable range. If the backlash amount BL is within the allowable range, the NC machine tool NC is determined to be in a correct state and can be used continuously as it is (YES), and the process proceeds to step S51.

In the next step S51, the backlash correction value is restored to the original value, and the process proceeds to step S60. The original value is the value stored in the cache memory in step S2.

In step S60, the backlash quantity BL calculated in step S40 and the contents of the numerical control machine NC that can be continuously used as they are displayed, and the control is Ended (END). The display can be performed on the display unit of the upper computer PC (the same applies to the display). The upper computer device PC transmits the diagnosis result of step S60 to an external communication terminal via an electronic mail (mail) and/or the internet (internet). The manager of the NC machine tool NC can know the status of the NC machine tool NC whether the NC machine tool NC is left or even left from the host computer device PC.

In contrast, if the backlash quantity BL is out of the allowable range in step S50, it is determined that the machine system of the NC machine tool NC is not in a correct state and cannot be used continuously without any change (NO), and the process proceeds to step S70.

In the next step S70, the diagnostic maintenance device of the numerical controller 17 corrects the backlash correction value belonging to the numerical control parameter for correcting the backlash quantity BL, and determines whether or not the NC tool NC can be returned to a correct state, that is, whether or not the backlash quantity BL is within a predetermined usable range. The usable range is a range larger than the allowable range, and includes the allowable range. If the backlash amount BL is too large, the NC machine tool NC cannot be used (NO) when the NC machine tool NC is out of the usable range, and the process proceeds to step S75. In this regard, when the backlash correction value is within the usable range (YES), the NC machine tool NC is used by adjusting the backlash correction value, and the process proceeds to step S90.

In step S90, the calculated backlash amount BL and the contents of the backlash correction value to be changed are displayed, and the process proceeds to step S100. In the next step S100, the backlash correction value is changed. The calculation of the backlash correction value can be performed by a parameter rewriting device of the host computer device PC based on the calculated backlash amount BL. The parameter rewriting device of the host computer device PC rewrites the backlash correction value stored in the parameter storage device, and the process proceeds to step S110.

If necessary, in the next step S110, the power of the numerical control machine tool NC is stopped in accordance with a command from the host computer device PC, and the control (END) is ended. After the next restart, the NC machine tool NC machines the workpiece by executing the workpiece machining program and the new backlash correction value after the rewriting. In addition, in the above-mentioned steps S80 to S110, the upper computer device PC also transmits the diagnosis result to an external communication terminal via e-mail and/or the internet, and notifies that the backlash amount BL and the backlash correction value have been rewritten and warns. The manager of the numerical control machine tool NC can know the status of the numerical control machine tool NC whether the manager leaves the numerical control machine tool NC or even leaves the upper computer device PC.

In response to this, in step S75, the backlash correction value is restored to the original value, and the process proceeds to step S80. The original value is the value stored in the cache memory in step S2. Even if it is determined in step S70 that the backlash amount is excessive, the numerical control machine tool NC can be used temporarily and continuously by the execution of step S75.

In step S80, a warning is displayed that a problem occurs in the indexing accuracy of the rotary disk 12 even if the backlash correction value is changed, and that maintenance (overhauls) of the mechanical system including the worm wheel 28 is required, and this control is Ended (END).

Fig. 7 is a diagram relating to step S30 and illustrating the collected numerical control information, and fig. 8 is a graph showing an enlarged portion of the two-dot chain line in fig. 7. In fig. 7 and 8, the horizontal axis represents time [ msec ] and the vertical axis represents torque command TCMD. The numerical control unit 17 outputs a torque command TCMD to the servo motor SM every 1[ msec ], and first rotates the servo motor SM in the positive direction for a period Ta, and rotates the worm screw 27 in the clockwise direction as shown in fig. 5 (a). Next, a stop period Tb is set, the servomotor SM is then rotated in reverse in the period Tc, and the worm screw 27 is rotated counterclockwise as shown in fig. 5(C) to reduce the backlash. The positive rotation of the servo motor SM means a clockwise rotation of the worm wheel 28 shown in fig. 5(a), and may be a counterclockwise rotation of the worm wheel 28, which is not shown. The measurement direction of the backlash amount BL may be any direction around clockwise/counterclockwise.

While the backlash in the reverse rotation shown enlarged in fig. 5(B) is reduced by the reverse rotation shown in fig. 5(C), the torque command TCMD is small because the worm screw 27 is driven by the servo motor SM and the worm wheel 28 is not driven. After the backlash is reduced, the servo motor SM drives the worm screw 27 and the worm wheel 28, and thus the torque command TCMD increases.

In fig. 7, torque command TCMD is a positive value from time t1 to time t2 included in period Ta. At time t2, torque command TCMD transitions from increasing to decreasing and then becomes negative. At the next time t3, the torque command TCMD for reverse rotation rises sharply on the negative side.

Next time t4 is a point when the substantially constant torque command TCMD that repeats the increase and decrease decreases a large number of times in succession. At time t4, the backlash is completely filled and the worm wheel 28 begins to rotate in the counterclockwise direction (fig. 5 (C)).

In step S40, as shown in fig. 8, the backlash reduction time t4 is determined from the increase and decrease of the patterned torque command TCMD. The time referred to in this specification is the same as the time.

During the period from time t3 to time t4, the worm wheel 28 stops although the servomotor SM rotates in accordance with the reverse rotation command. In other words, the time to reduce backlash is roughly (t4-t 3).

The backlash quantity BL of the mechanical system is calculated from the backlash reduction time (t4-t3) [ msec ], the programmed feed rate [ deg/msec ] and the pitch diameter [ mm/] of the worm wheel 28.

As an example, the backlash correction value is rewritten based on the absolute backlash amount BL calculated from fig. 8 as described above.

As another example, with respect to a new product of the NC machine tool NC when the NC machine tool NC is shipped from a manufacturer (maker) or a substantially new product of the NC machine tool NC when a user uses the NC machine tool NC for the first time, the fig. 8 is analyzed as described above with respect to the initial use period, and the time point (time t4) when the backlash amount BL of the counter rotation is reduced and the worm wheel 28 starts to operate is determined and stored. After that, for example, several months or even several years after the numerical control machine tool NC is used, the above-described program is executed, and the point at which the backlash amount BL in the reverse rotation at this time is reduced and the worm wheel 28 starts to operate is similarly determined (time t8 described later). When the NC machine tool NC is used for years, the backlash quantity BL increases due to wear and the like, and therefore the time t8 is later than the time t 4. Therefore, the relative comparison between time t8 and time t4 calculates the increase in backlash amount BL with time, and the backlash correction value is rewritten in accordance with the increase in backlash amount BL.

Fig. 9 and 10 are analysis data for calculating the backlash amount after several months or even years of use of the NC machine tool NC. First, from time t5 to time t6 shown in fig. 9, torque command TCMD is a positive value. At time t6, torque command TCMD changes from increasing to decreasing, and then becomes a negative value. Fig. 10 is a graph showing an enlarged portion of the two-dot chain line shown in fig. 9.

At time t7 after time t6, the torque command TCMD instantaneously rises quickly. Time t8 is a time when torque command TCMD decreases a large number of times in succession.

The subsequent backlash quantity BL is calculated from the time (t8-t7) for reducing the backlash in the reverse rotation [ msec ], the programmed feed rate [ deg/msec ] and the pitch diameter [ mm/] of the worm wheel shown in FIG. 10. In order to avoid overlapping with the description of fig. 7 and 8, detailed description of fig. 9 and 10 will be omitted.

Further, as shown in fig. 10, when data of the torque command TCMD outputted for each [ msec ], the graph of the torque command TCMD appears jagged, and it is difficult to judge the timing when the torque command TCMD decreases a plurality of times continuously or increases a plurality of times continuously.

Therefore, in the supervisory control program according to the present embodiment, the torque command TCMD is leveled.

Specifically, for example, an average value of five consecutive points of the torque command TCMD is obtained. Then, a graph (fig. 11) is created which is normalized by using the five-point average value. Fig. 11 is a graph obtained by flattening fig. 10. Since the torque command TCMD shown in fig. 11 after the leveling does not increase or decrease repeatedly and sharply as compared with the torque command TCMD shown in fig. 10 without leveling, it is easy to determine the time t8 at which the torque command TCMD decreases continuously a plurality of times.

Alternatively, for example, an average value of ten consecutive points of the torque command TCMD is obtained. Then, a graph was created which was normalized using a ten-point average value (fig. 12). Fig. 12 is a graph obtained by flattening fig. 10.

By the leveling shown in fig. 12, the time t8 at which the torque command TCMD decreases a plurality of times in succession can be easily determined.

Alternatively, for example, an average of consecutive fifteen points of torque command TCMD is found. Then, a graph was created which was normalized using the fifteen-point average value (fig. 13). Fig. 13 is a graph obtained by flattening fig. 10.

By the leveling shown in fig. 13, the time t8 at which the torque command TCMD decreases a plurality of times in succession can be easily determined.

Alternatively, for example, an average of twenty consecutive points of torque command TCMD is found. Then, a graph was created which was normalized using the twenty-point average value (fig. 14). Fig. 14 is a graph obtained by flattening fig. 10.

By the leveling shown in fig. 14, the time t8 at which the torque command TCMD decreases a plurality of times in succession can be easily determined.

In addition, when the numerical control information to be averaged is too large in the case of the continuous multi-point leveling as shown in fig. 11 to 14, the graph becomes excessively flat, and the determination at time t8 becomes difficult instead. Therefore, it is preferable that the leveling be performed appropriately so that the numerical control information to be averaged is not too small or too large.

In the present embodiment, the backlash amount can be calculated not only at one position in the circumferential direction of the rotating disk 12 but also at a plurality of positions separated in the circumferential direction. For example, in the present embodiment, the backlash amounts BL1 to BLm can be calculated as the backlash amount BL1 at the circumferential position R1 and the backlash amount BL2 … at the circumferential position R2 at predetermined circumferential positions R1, R2 to Rm shown in fig. 4. For example, R1 to Rm are at predetermined positions (m ═ 8) at 45 ° intervals with respect to the center of the rotating disk 12.

Since the worm wheel 28 has a far larger diameter than the worm screw 27, the worm screw 27 commonly meshes with the circumferential positions R1 to Rm of the worm wheel 28. In addition, the angular positions of the circumferential positions R1 through Rm of the worm wheel 28 correspond to the angles of the rotary disk 12.

Depending on the shape of the workpiece clamped on the rotary disk 12, the indexing of the rotary disk 12 may be biased to a specific circumferential region, and the worm wheel 28 may be biased to wear in the circumferential region.

According to the present embodiment, when the backlash amount BL of one of the positions R1 to Rm falls outside the allowable range, a warning is displayed to perform the inspection of the worm wheel 28, and the correct operation of the numerical control machine tool NC can be achieved.

The backlash correction value in step S100 may be rewritten based on the average value of the backlash amounts at the circumferential positions R1 to Rm.

The present embodiment further includes a pitch error correction function to ensure the indexing accuracy of the rotary disk 12 for a long period of time.

To illustrate the indexing accuracy of the rotating disk 12, it is possible that the rotating disk 12 of a mechanical system may contain tooth pitch errors that exceed acceptable values. Therefore, in the present embodiment, the pitch error correction amount corresponding to the backlash amount BL is calculated at each of the circumferential direction positions R1 to Rm of the worm wheel 28. The numerical control machine tool NC rewrites the pitch error correction value based on the calculated pitch error correction value.

For example, every time the worm screw 27 rotates the worm wheel 28 once, that is, every 5 degrees (5 pitches), the backlash amount BL is calculated for every pitch of 0 °, 5 °, 10 °, 15 °, 355 °, and 360 ° (═ 0 °) of each circumferential position of the worm wheel 28. The diagnostic maintenance shown in fig. 6 is performed for each circumferential position of 0 °, 5 °, 10 °, 15 ° to 355 °, and 360 ° (═ 0 °) for each pitch. According to the present embodiment, in the case where the worm screw 27 rotates by an integral multiple corresponding to one rotation of the worm wheel 28, the indexing accuracy of the worm wheel 28 at an arbitrary angle is ensured for a long period of time.

For example, when the worm wheel 28 is worn at one 30 ° in the circumferential position, the backlash correction value is rewritten at the 30 ° in the circumferential position (step S100), and the previous backlash correction value is applied at the other circumferential position (step S60). According to the present embodiment, even when the worm wheel 28 is worn on one side, the pitch error caused by the wear is corrected, and the indexing accuracy is ensured for a long period of time.

In addition, the pitch error correction may be performed only at an arbitrary circumferential position, as in the case of performing the correction only at the circumferential position used for the positioning at the actual indexing angle, in addition to the correction performed for all the pitches (circumferential positions) constituting the entire circumference of the worm wheel 28 as described above.

The diagnostic and maintenance system of the present embodiment includes one or more NC tools NC #1 to NC # n, one host computer device PC, and a network device NW connecting the plurality of NC tools NC #1 … and the host computer device PC, wherein each NC tool NC includes a servomotor SM that powers the NC tool NC and a numerical controller 17 that controls the servomotor SM. The numerical controller 17 includes: a monitoring device for monitoring the servo data (numerical control information) inputted and outputted between the numerical control part 17 and the servo motor SM; and an uploading device for uploading the servo data monitored by the monitoring device to the upper computer device PC through the network device NW. The upper computer PC has a diagnosis and maintenance device for diagnosing the NC machine tool NC based on the uploaded servo data.

According to the present embodiment, an operator can know the diagnosis results of the plurality of NC tools NC #1 to NC # n through one host computer device PC, and does not need to assign an operator to each NC tool NC. In addition, if the upper computer device PC is provided separately from the plurality of NC tools NC #1 to NC # n, a remote diagnosis and maintenance system for the NC tool NC is realized. Further, when the NC tools NC #1 to NC # n are distributed in a plurality of factories, an integrated diagnosis and maintenance system of the NC tool NC is realized.

In addition, the numerical control information monitored by the monitoring apparatus of the present embodiment is selected from servo data including: a speed command VCMD output from the numerical controller 17 to the servo motor SM; a torque command TCMD output from the numerical controller 17 to the servo motor SM; a SPEED feedback SPEED output from an encoder EC provided in the servo motor SM to the numerical controller 17; a position feedback POSF output from the encoder EC to the numerical controller 17; and the difference (error) between the SPEED command VCMD and the SPEED feedback SPEED.

The host computer device PC according to the present embodiment includes a parameter rewriting device for rewriting numerical control parameters related to the operation of the numerical control machine tool NC. When the diagnostic result diagnosed by the diagnostic maintenance device in step S50 of fig. 6 falls within the allowable range and within the usable range, the parameter rewriting device proceeds to step S60 and does not rewrite the numerical control parameter. Further, when the diagnostic result diagnosed by the diagnostic maintenance device in step S70 falls outside the allowable range and is within the usable range, the parameter rewriting device proceeds to steps S90 and S100, and rewrites the numerical control parameter. Further, when the diagnostic result diagnosed by the diagnostic maintenance device falls outside the allowable range and outside the usable range in step S70, the parameter rewriting device proceeds to step S80 and outputs a warning.

The diagnostic and maintenance device of the present embodiment calculates the backlash quantity BL at the meshing position between the worm screw 27 (drive gear) driven by the servo motor SM and the worm wheel 28 (driven gear) meshing with the worm screw 27 (step S40), and diagnoses whether the backlash quantity BL is within an allowable range (step S50) and whether the backlash quantity BL is within a usable range (step S70). When the calculated backlash amount BL falls outside the allowable range and is within the usable range (YES in step S70), the parameter rewriting device of the host computer device PC proceeds to steps S90 and S100, and rewrites the numerical control parameter in accordance with the backlash amount.

In step S40, the diagnostic maintenance device of the present embodiment analyzes the torque command TCMD and calculates the backlash amount BL from the change in the torque command TCMD and the speed command VCMD shown in fig. 8.

In the monitoring management program of the present embodiment, the servo motor SM is first driven in the forward direction as shown in fig. 5 a, and then the servo motor SM is driven in the reverse direction as shown in fig. 5C, and the diagnostic and maintenance device calculates the backlash amount BL in the reverse direction with respect to the driving of the servo motor SM in the forward direction (fig. 5B).

In addition, the worm wheel 28 belonging to the driven gear of the present embodiment is larger than the worm screw 27 belonging to the drive gear, and the worm screw 27 rotates a plurality of times while the worm wheel 28 rotates once. The monitoring management program downloaded to the numerical controller 17 drives the servo motor SM in the forward direction and the reverse direction at a plurality of positions R1 to Rm of the worm wheel 28 shown in fig. 4. The diagnostic maintenance device of the host computer PC calculates the backlash amounts BL1 to BLm of the worm wheel 28 at the plurality of positions R1 to Rm, respectively, and diagnoses and maintains the numerical control machine NC based on the plurality of backlash amounts BL1 to BLm.

The diagnostic and maintenance device of the present embodiment levels the monitored torque command TCMD as shown in fig. 11 to 14, determines the time t8 at which the leveled torque command TCMD continuously increases or decreases a plurality of times, and calculates the temporal change amount of the backlash quantity BL from the difference between the previously determined time (t4-t3) (fig. 8) and the subsequently determined time (t4-t 3).

The worm screw 27 of the present embodiment is a drive gear, the worm wheel 28 is a driven gear, the worm wheel 28 is coaxially attached to the turntable 12, and the worm screw 27 transmits the driving force of the servo motor SM to the turntable 12.

Next, a modified example of the logic for calculating the backlash amount BL executed in step S40 will be described.

Fig. 15 is a graph showing a temporal change in torque command TCMD in the modification. In this modification, the backlash quantity BL is calculated by the logic for calculating the torque limit override function. As a calculation logic, first, the servo motor SM is driven in the positive direction with the speed command VCMD set to a positive value. At this time, as shown in fig. 15, torque command TCMD is set to a positive value.

Then, in a predetermined period from time t9 to time t10, the shutdown is performed so that the speed command VCMD becomes zero.

Then, the servo motor SM is driven in the reverse direction, assuming that the speed command VCMD is negative. Torque command TCMD sharply decreases to a negative value, and then reaches a peak (peak) at time t 11. The worm screw 27 starts to rotate counterclockwise after being started, and performs the backlash reducing operation. In addition, the torque command TCMD that is a negative value becomes substantially fixed by the time t11 immediately after the time t 10. The term "substantially constant" as used herein means that the torque command TCMD repeatedly increases and decreases. At the end of the substantially constant period, the torque command TCMD is gradually decreased.

When the torque command TCMD reaches the predetermined torque limit α at time t12 at which a sufficient time has elapsed after time t10, it is determined that the backlash reduction operation is completed, the torque limit α is larger than the torque command TCMD at time t11, and after time t12, the program moves to the next single joint (block).

Since the torque limit override function is a function of determining the position (angle) at time t12 when the torque command TCMD exceeds the torque limit value, the backlash quantity BL of the mechanical system is calculated from the moved angle, the feed speed command of the program, and the pitch diameter [ mm/] of the worm wheel 28. Or the temporal change amount of the backlash quantity BL is calculated from the difference between the previously detected time (t12-t10) and the subsequently detected time (t12-t 10).

According to the modification shown in fig. 15, after the servo motor SM is driven in the forward direction, the stop is executed so that the speed command VCMD becomes 0 before the servo motor SM is driven in the reverse direction, the diagnostic and maintenance device stores a predetermined value (a predetermined value apart from 0) larger than the torque command (the torque command TCMD at time t 11) required for starting the worm screw 27 as the torque limit value α in advance, and detects a time t12 when the monitored torque command TCMD exceeds the torque limit value α after the stop is completed (time t10), whereby the backlash quantity BL can be calculated more easily than the calculation logic shown in fig. 8, 11 to 14.

While the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the embodiments shown in the drawings. The embodiment shown in the drawings can be modified or changed in various ways within the same range as or equivalent to the present invention. For example, a part of the structure may be extracted from the one embodiment and another part of the structure may be extracted from the other embodiment, and these extracted structures may be combined.

[ industrial applicability ]

The present invention can be effectively used in numerical control devices such as machine tools.

Claims

1. A diagnostic and maintenance system for a numerical control machine tool, comprising: one or more numerical control machine tools, an upper computer device and a communication device for transmitting and receiving data between the numerical control machine tools and the upper computer device;

the numerical control machine tool includes: a servomotor as a power of the numerical control machine tool; and a numerical control part for numerically controlling the servo motor;

the numerical control unit includes: a monitoring device for monitoring the numerical control information input and output between the numerical control part and the servo motor; the uploading device uploads the numerical control information monitored by the monitoring device to the upper computer device through the communication device;

the upper computer device has a diagnosis and maintenance device which diagnoses the numerical control machine tool according to the uploaded numerical control information, downloads numerical control parameters to the numerical control machine tool when the diagnosis result falls outside an allowable range and is within a usable range, and rewrites the numerical control parameters memorized in the numerical control machine tool.

2. The diagnostic and maintenance system of a numerically controlled machine tool according to claim 1, wherein the numerical control parameter is not rewritten when a diagnostic result diagnosed by the diagnostic and maintenance device falls within an allowable range and is within a usable range;

and outputting a warning when the diagnosis result diagnosed by the diagnosis and maintenance device falls outside the allowable range and outside the usable range.

3. The system of claim 1, wherein the numerical control information monitored by the monitoring device is selected from servo data comprising: a speed command output from the numerical controller to the servomotor; a torque command output from the numerical controller to the servomotor; a speed feedback unit which outputs a speed feedback from a feedback device provided in the servo motor to the numerical controller; position feedback, output from the feedback machine to the numerical controller; and the difference (error) of the velocity command and the velocity feedback.

4. The system of claim 2, wherein the numerical control information monitored by the monitoring device is selected from servo data comprising: a speed command output from the numerical controller to the servomotor; a torque command output from the numerical controller to the servomotor; a speed feedback unit which outputs a speed feedback from a feedback device provided in the servo motor to the numerical controller; position feedback, output from the feedback machine to the numerical controller; and the difference (error) of the velocity command and the velocity feedback.

5. The diagnostic and maintenance system for a numerical control machine tool according to claim 3 or 4, wherein the diagnostic and maintenance device calculates a backlash amount of an engagement position between a drive gear driven by the servomotor and a driven gear engaged with the drive gear, diagnoses whether the backlash amount is within the allowable range and whether the backlash amount is within the usable range, and rewrites the numerical control parameter of the backlash correction value based on the backlash amount when the calculated backlash amount falls outside the allowable range and is within the usable range.

6. The system of claim 5, wherein the diagnostic and maintenance device executes a supervisory program for driving the servomotor in a forward direction first and then in a reverse direction, and calculates the backlash amount in the reverse rotation.

7. The system of claim 6, wherein the diagnostic and maintenance device analyzes the torque command, determines that the driven gear has started to operate due to a change in the torque command, and calculates the backlash amount.

8. A diagnostic and maintenance system for a numerically controlled machine tool as in claim 7, wherein the driven gear is of a larger diameter than the drive gear and rotates at a predetermined pitch upon each rotation of the drive gear;

the monitoring management program drives the servo motor in the forward direction and the reverse direction at a plurality of positions of the driven gear corresponding to the pitch;

the diagnostic maintenance device calculates the backlash amount of each of the plurality of positions, and diagnoses and maintains the numerical control machine tool based on the plurality of backlash amounts to correct the pitch error of the driven gear.

9. The diagnostic and maintenance system of a numerically controlled machine tool as claimed in claim 7, wherein the diagnostic and maintenance device normalizes the monitored torque command;

and the time when the torque command after the leveling continuously increases or decreases a plurality of times is judged, and the backlash amount is calculated by multiplying the time from the time when the servomotor starts to be driven in the reverse direction to the time when the judgment is made by a constant speed of the program command.

10. The system of claim 7, wherein the supervisory control program executes a stop for setting the speed command to 0 after the servo motor is driven in the forward direction and before the servo motor is driven in the reverse direction;

the diagnosis and maintenance device memorizes a preset value as a torque limit value in advance;

a time point when the monitored torque command exceeds the torque limit value after the stop is detected, and a backlash amount is calculated based on the time point.

11. The diagnostic and maintenance system of a numerically controlled machine tool as claimed in claim 7, wherein the monitoring device monitors an initial torque command pertaining to the torque command at an initial stage of use of the numerically controlled machine tool;

the uploading device uploads the initial torque instruction to the upper computer device;

the diagnostic and maintenance device compares the initial torque command with the torque command after several months from the initial use to calculate the increase in backlash.

12. The diagnostic and maintenance system of a numerically controlled machine tool as claimed in any one of claims 3, 4, and 6 to 11, wherein the driving gear and the driven gear are a worm screw and a worm wheel;

the worm wheel is coaxially arranged on the rotating disc;

the worm screw transmits the driving force of the servo motor to the rotating disk.

13. The system for diagnosing and maintaining a numerical control machine tool according to any one of claims 1 to 4 and 6 to 11, wherein the host computer device tries to run the numerical control machine tool so that a state of a mechanical system of the numerical control machine tool is adjusted to be constant before the diagnostic maintenance of the numerical control machine tool by the diagnostic maintenance device is performed.

14. The system for diagnosing and maintaining a numerical control machine tool according to any one of claims 1 to 4 and 6 to 11, wherein the host computer device notifies the outside of a result of the diagnosis and maintenance of the numerical control machine tool by the diagnosing and maintaining device through an electronic mail and/or the internet.